Dual inlet microchannel device and method for using same

ABSTRACT

A dual inlet microchannel device and a method for using the device to perform a flow-through kinetic assay are described. A microplate having an array of the dual inlet microchannel devices and in particular their specially configured flow chambers is also described. Several embodiments of the dual inlet microchannel devices and specially configured flow chambers are also described.

The entire disclosure of publications, patents, and patent documentsmentioned herein are incorporated by reference.

CLAIM OF PRIORITY

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 11/784,130 filed on Apr. 5, 2007 now U.S. Pat. No.7,824,624 and entitled “Closed Flow-Through Microplate and Methods forUsing and Manufacturing Same”.

BACKGROUND

The disclosure relates to a dual inlet microchannel device and a methodfor using the dual inlet microchannel device to perform a flow-throughkinetic assay.

SUMMARY

In embodiments, the disclosure provides a dual inlet microchannel devicecomprising a body having formed therein: a first fluid inlet; a secondfluid inlet; a fluid outlet; and a flow chamber.

In embodiments, the disclosure provides a microplate incorporating thedual inlet microchannel device as describe herein.

In embodiments, the disclosure provides a method for performing aflow-through kinetic assay using the dual inlet microchannel device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are diagrams of a dual inlet microchannel device, inembodiments of the disclosure.

FIGS. 2A-2E are diagrams illustrating different views of a closedflow-through microplate, in embodiments of the disclosure.

FIGS. 3A-3B are diagrams illustrating a fluid delivery system coupled tothe closed flow-through microplate, in embodiments of the disclosure.

FIG. 4 is a flowchart illustrating the steps of a method for using theclosed flow-through microplate to perform a flow-through kinetic assay,in embodiments of the disclosure.

FIGS. 5-11 are diagrams and plots which are used to help explain theconfiguration of a flow chamber which is used in the closed flow-throughmicroplate (and the dual inlet microchannel device), in embodiments ofthe disclosure.

FIGS. 12A-12B are diagrams of a dual inlet microchannel device, inembodiments of the disclosure.

FIGS. 13A-13B are diagrams of a dual inlet microchannel device, inembodiments of the disclosure.

DETAILED DESCRIPTION

Various embodiments of the disclosure are described in detail withreference to drawings, if any. Reference to various embodiments does notlimit the scope of the invention, which is limited only by the scope ofthe claims attached hereto. Additionally, any examples set forth in thisspecification are not limiting and merely set forth some of the manypossible embodiments for the claimed invention.

The indefinite article “a” or “an” and its corresponding definitearticle “the” as used herein means at least one, or one or more, unlessspecified otherwise.

“Include,” “includes,” or like terms means including but not limited to.

“About” modifying, for example, the quantity of an ingredient in acomposition, concentrations, volumes, process temperature, process time,yields, flow rates, pressures, and like values, and ranges thereof,employed in describing the embodiments of the disclosure, refers tovariation in the numerical quantity that can occur, for example, throughtypical measuring and manipulation procedures; through inadvertent errorin these procedures; through differences in the manufacture, source, orpurity of starting materials or ingredients used to carry out themethods; and like considerations. The term “about” also encompassesamounts that differ due to, for example, aging of a formulation having aparticular initial concentration, or mixture, and amounts that differdue to processing a formulation with a particular initial concentration,or mixture. Whether modified by the term “about” the claims appendedhereto include equivalents to these quantities.

“Optional” or “optionally” or like terms generally refer to, forexample, that the subsequently described event or circumstance can orcannot occur, and that the description includes instances where theevent or circumstance occurs and instances where it does not.

“Consisting essentially of” in embodiments refers, for example, a dualinlet microchannel device comprising a body having formed therein: afirst fluid inlet; a second fluid inlet; a fluid outlet; and a flowchamber, as defined herein, a microplate incorporating the dual inletmicrochannel device as describe herein, a method for performing aflow-through kinetic assay using the dual inlet microchannel device asdescribe herein, and can include the components or steps listed in theclaim, plus other components or steps that do not materially affect thebasic and novel properties of the article, device, apparatus, system,and methods of making and use of the disclosure, such as a particularreactant, a particular additive or ingredient, a particular agent, aparticular surface condition, or like structure, material, process, orcomputational variable selected.

Many areas of biological research use microchannel devices with embeddedsensors to help perform increasingly sensitive and time-constrainedflow-through kinetic assays. These flow-through kinetic assays areperformed to detect biomolecular interactions such as material bindings,adsorptions, and like interactions that are helpful, for example, withtesting new drugs. A typical flow-through kinetic assay is performed byfirst immobilizing a target on a sensing surface within a microchannel,and then flowing a buffer solution over the sensing surface to establisha baseline measurement. Then, a drug solution (or analyte solution) isflowed through the microchannel for a prescribed period of time, oftencalled the association time, to enable the detection of an associationresponse. Next, the buffer solution is flowed again through themicrochannel to enable the detection of an dissociation response. Thesensor responses during these steps are used to calculate the rate atwhich the drug associates with the immobilized target and thendissociates from the immobilized target. The response times,particularly during the association phase, can be on the order of about1-100 seconds. Thus, to be able to monitor the shortest response timesit is helpful that the switching time between the flowing of the buffersolution, the drug solution and then the buffer solution again be atleast as short, and preferably much shorter than the time it takes thedrug to completely bind to the immobilized target. Otherwise, theresulting kinetic response will be confounded by the slow fluidicswitching. Accordingly, a challenge in the design of a microchanneldevice (or microfluidic flow cell) and the fluidic system (whichsupplies the buffer solution and the drug solution) is to minimize thisswitch time so faster sensor responses can be resolved. This and otherchallenges are satisfied by a dual inlet microchannel device and methodof the disclosure.

In embodiments, an array of the dual inlet microchannel devices, and inparticular their specially configured flow chambers, can be incorporatedwithin a microplate. Several embodiments of the dual inlet microchanneldevices and specially configured flow chambers are also described.

In embodiments, the flow chamber can include, for example: i) a firstflow restrictive mechanism (i.e., a restrictor; e.g., porous material,weir, flow restrictive neck) associated with the first fluid inlet; ii)a second flow restrictor (e.g., porous material, weir, flow restrictiveneck) associated with the second fluid inlet; iii) a central portionhaving one corner of one end associated with the first flow restrictorand another corner of the one end associated with the second flowrestrictor; and iv) an outlet portion associated with the fluid outletand an opposite end of the central portion, wherein the opposite end isdirectly opposite from both an opening of the one corner and an openingof the another corner associated with the one end of the centralportion. The disclosure also includes a method for performing aflow-through kinetic assay using the dual inlet microchannel device.

In embodiments, the disclosure provides a microplate comprising: anupper plate including a top surface, a body, and a bottom surface, wherethe top surface has located thereon a sealing substance which has one ormore fluid delivery-removal sealing interfaces where each fluiddelivery-removal sealing interface can have at least two fluid inletports and at least one fluid outlet port; the body having one or morefluid delivery-removal channels extending therethrough where each fluiddelivery-removal channel has at least two fluid inlet channels and atleast one fluid outlet channel which are respectively aligned with theat least two fluid inlet ports and the at least one fluid outlet portthat are located within the corresponding fluid delivery-removal sealinginterface of the sealing substance; and a lower plate including a topsurface which is attached to the bottom surface of the upper plate suchthat one or more flow chambers are present therebetween, where each oneof the flow chambers is in fluid communication with a corresponding oneof the fluid delivery-removal channels extending through the body of theupper plate. In embodiments, each flow chamber can further include, forexample: i) a first flow restrictor (e.g., porous material, weir, flowrestrictive neck) associated with one of the corresponding fluid inletports; ii) a second flow restrictor (e.g., porous material, weir, flowrestrictive neck) associated with another one of the corresponding fluidinlet ports; iii) a central portion having one end associated with thefirst flow restrictor and the second flow restrictor; and iv) an outletportion associated with the corresponding fluid outlet port and anopposite end of the central portion. The disclosure also includes amethod for performing a flow-through kinetic assay using the microplate.

Referring to FIGS. 1A-1B, there are respectively illustrated across-sectional side view and a cross-sectional top view of a dual inletmicrochannel device 100 in accordance with the disclosure. The dualinlet microchannel device 100 includes a body 102 having located thereina first fluid inlet 104, a second fluid inlet 106, a fluid outlet 108, aflow chamber 110, and an optional sensor 112. The flow chamber 110includes a first inlet portion 114, a first flow restrictive neck 116(flow restrictor 116), a second inlet portion 118, a second flowrestrictive neck 120 (flow restrictor 120), a central portion 122, andan outlet portion 124. As can be seen, the first fluid inlet 104 is influid communication with the first inlet portion 114. The first inletportion 114 is in fluid communication with the first flow restrictiveneck 116. Likewise, the second fluid inlet 106 is in fluid communicationwith the second inlet portion 118. The second inlet portion 106 is influid communication with the second flow restrictive neck 120. The firstand second flow restrictive necks 116 and 120 are in fluid communicationwith one end of the central portion 122. If desired, the central portion122 can have a flow restrictive neck 126 which is in fluid communicationwith the first and second flow restrictive necks 116 and 120. The sensor112 if used would have a sensing surface that would be located withinthe central portion 122. Lastly, the outlet portion 124 would be influid communication with the fluid outlet 108 and an opposite end of thecentral portion 122. The dual inlet microchannel device 100 and inparticular the flow chamber 110 is specially configured so as tominimize the fluid switching time that is desired when performing aflow-through kinetic assay. A discussion of the specially configuredflow chamber 110 is provided below with respect to an exemplarymicroplate 200 which has an array of the specially configured flowchambers incorporated therein.

In FIGS. 2A-2E, there are drawings illustrating different views of anexemplary 96-well closed flow-through microplate 200 in accordance withthe disclosure (the closed flow-through microplate 200 can have anynumber of wells such as for example 24, 96, 384 or 1536 wells). In FIG.2A, there is a perspective view of the 96-well closed flow-throughmicroplate 200 which is configured as a microplate 2-plate stack thathas an upper plate 202 (well plate 202) attached to a lower plate 204(sensor plate 204) (the microplate 200 is shown with some “shaded areas”but can be, for example, transparent where the “shaded areas” are usedhere to help illustrate the different features of the microplate 200).The well plate 202 has a series of peripheral supports 206 extendingdownward therefrom which rest on a surface (e.g., table, supportplatform) and protect a bottom surface 208 of the sensor plate 204.

As shown in FIG. 2A, the well plate 202 has a top surface 210 on whichthere is a sealing substance 212 which is divided into 96-fluiddelivery-removal sealing interfaces 214 (the sealing substance 212 hasfour distinct sections 212 a, 212 b, 212 c and 212 d). In thisparticular example, each of the fluid delivery-removal sealinginterfaces 214 has two inlet ports 216 a and 216 b and one outlet port218. However, each of the fluid delivery-removal sealing interfaces 214could have more than two inlet ports 216 and any number of outlet ports218. For example, each fluid delivery-removal sealing interface 214could have three inlet ports 216 and three outlet ports 218. FIG. 2B isa partial view of the top surface 210 of the well plate 202 which showsdepressions 211 located therein in which there is deposited the sealingsubstance 212.

In FIG. 2C, there is shown an isometric view of a partial sectionedmicroplate 200. As can be seen, the well plate 202 has a body 220 withan array of 96-fluid delivery-removal channels 222. Each set of fluiddelivery-removal channels 222 includes two inlet channels 224 a and 224b and one outlet channel 226 (the outlet channel 226 is shown in FIG.2D). Plus, each set of fluid delivery-removal channels 222 is alignedwith a corresponding one of the fluid delivery-removal sealinginterfaces 214 such that the inlet channels 224 a and 224 b are alignedwith the inlet ports 216 a and 216 b and the outlet channel 226 isaligned with the outlet port 218. In addition, the microplate 200includes the sensor plate 204 which has a top surface 228 attached to abottom surface 230 of the well plate 202 such that there is one flowchamber 232 formed therein which corresponds with each fluiddelivery-removal channel 222 that includes two inlet channels 224 a and224 b and one outlet channel 226 which extend through the body 120 andopen at the bottom surface 230 of the well plate 202 (the flow chamber232 discussed below has the same or similar configuration as the flowchamber 110 discussed above with respect to FIGS. 1A-1B).

As can be seen, the sensor plate 204 also has sensors 236 incorporatedtherein such that there is one sensor 236 associated with each flowchamber 232 (note: if desired there can be more than one sensor 236associated with each flow chamber 232). The sensor 236 could be asurface plasmon resonance (SPR) sensor 236 or a waveguide gratingcoupler (WGC) sensor 236. For a discussion of the WGC sensor 236 seeU.S. Pat. No. 4,815,843. Alternatively, the use of the sensor 236 isoptional as discussed below with respect to method 400.

FIG. 2D is a cross-sectional side view of one well 234 located withinthe microplate 200 (this is a different view than the wells 234 shown inFIG. 2C). The well 234 includes one fluid delivery-removal sealinginterface 214 (sealing substance 212) that is located on the top surface210 of the well plate 202. The fluid delivery-removal sealing interface214 includes two inlet ports 216 a and 216 b (only one shown) and oneoutlet port 218 which are connected to one of the fluid delivery-removalchannels 222 which includes two input channels 224 a and 224 b (only oneshown) and one output channel 226 all of which open-up into the flowchamber 232. The flow chamber 232 (flow-through channel 232) because ofthe interconnected inlet ports 216 a and 216 b and inlet channels 224 aand 224 b and the interconnected outlet port 218 and outlet channel 226forms a closed fluid delivery-removal system. The sensor plate 204 alsohas one sensor 236 incorporated therein that has a sensing surfacewithin the flow chamber 232.

The well plate 202 and sensor plate 204 can be attached to one anotherby using any of several different attachment schemes. For instance, thewell plate 202 may have a bottom surface 230 which has ridge(s) 238extending therefrom which enables the formation of the flow chamber(s)232 when the well plate 202 is attached to the sensor plate 204 (seeFIGS. 2D-2E which illustrate a ridge 238 that creates a flow chamber 232when the well plate 202 is attached to the sensor plate 204). Ifdesired, the bottom surface 230 of the well plate 202 can also havechannels 240 formed therein which extend outside a perimeter of theridges 238 (see FIGS. 2D-2E). Each channel 240 is sized to contain theoverflow of an adhesive (not shown) which is used to attach the wellplate 202 to the sensor plate 204. Alternatively, a two-sided pressuresensitive adhesive film can be placed between and used to attach thewell plate 202 to the sensor plate 204. In this instance, the film hassections removed therefrom in a manner that each removed section formsone of the flow chambers 232 when the well plate 202 is attached to thesensor plate 204 (the film if used would negate the need to form theridge(s) 238 and channel(s) 240 within the bottom surface 230 of thewell plate 202).

FIGS. 3A-3B illustrate a fluid delivery system 300 coupled to the closedflow-through microplate 200 in accordance with the disclosure. FIG. 3Ais a partial perspective view of the fluid delivery system 300 securelyconnected via leak-free seals to the 96-well closed flow-throughmicroplate 200. The fluid delivery system 300 has 96 sets of fluiddelivery-removal tips 302 where each set of fluid delivery-removal tips302 has two fluid delivery tips 304 a and 304 b and one fluid removaltip 306. In operation, each set of fluid delivery-removal tips 302 areinserted into the corresponding fluid delivery-removal sealing interface214 on the microplate 200. In particular, each set of fluiddelivery-removal tips 302 has two fluid delivery tips 304 a and 304 band one fluid removal tip 306 respectively inserted into the two inletports 216 a and 216 b and the one outlet port 218 in the correspondingfluid delivery-removal sealing interface 214 on the microplate 200 (thesealing substance 212 selected can be o-rings and can be inserted intocounter-bored channels 224 a and 224 b and 226 located within the wellplate 202). FIG. 3B illustrates two fluid delivery tips 304 a and 304 b(only one shown) and the one fluid removal tip 306 have slightly smallerdiameters than the inner diameter for the corresponding two inlet ports216 a and 216 b and the corresponding outlet port 218 where therespective seals are effected at the bottom taper of the two fluiddelivery tips 304 a and 304 b and the fluid removal tip 306. Thesesealing interfaces can be referred to as “tip seals”. FIG. 3B is thesame as FIG. 2D except that two fluid delivery tips 304 a and 304 b(only one shown) and one fluid removal tip 306 are inserted into thewell 234 of the microplate 200. Alternatively, the two fluid deliverytips 304 a and 304 b (only one shown) and the one fluid removal tip 306can each have a diameter that is slightly larger than the inner diameterof the two inlet ports 216 a and 216 b and the one outlet port 218 inthe fluid delivery-removal sealing interface 214. In this case, thedifference in diameters enables a liquid tight seal to be formed betweenthe two fluid delivery tips 304 a and 304 b and the two inlet ports 216a and 216 b and between the one fluid removal tip 306 and the one outletport 218. These sealing interfaces can be referred to as “ring seals” asillustrated in the parent patent application. An exemplary fluiddelivery system 300 that could be used in this application has beendescribed in commonly-assigned U.S. Provisional Patent Application Ser.No. 60/817,724 filed Jun. 30, 2006, entitled “Fluid Handling System forFlow-Through Assay”.

FIG. 4 is a flowchart illustrating the steps of a method 400 for usingthe fluid delivery system 300 and the closed flow-through microplate 200to perform a flow-through kinetic assay in embodiments of thedisclosure. The method 400 can also be applied to the aforementioneddual inlet microchannel device 100. Beginning at step 402, the fluiddelivery system 300 and in particular the sets of fluid delivery-removaltips 302 are attached via compression-like seals to the microplate 200(see FIGS. 3A-3B). In this example, each set of fluid delivery-removaltips 302 has two fluid delivery tips 304 a and 304 b and one fluidremoval tip 306 that are respectively inserted into the two inlet ports216 a and 216 b and one outlet port 218 in the corresponding fluiddelivery-removal sealing interface 214 on the microplate 200. Thus, themicroplate 200 and in particular each flow chamber 232 is in fluidcommunication with two fluid delivery tips 304 a and 304 b and one fluidremoval tip 306. For clarity, only one flow chamber 232 and how thatflow chamber 232 is used to help perform a flow-through kinetic assay isdiscussed below but it should be appreciated that multiple flow chambers232 would typically be used at the same time to perform multipleflow-through kinetic assays with the microplate 200.

At step 404, the fluid delivery system 300 causes a buffer solution toflow through the first fluid delivery tip 304 a into and through theflow chamber 232 and then out the fluid removal tip 306 while aninspection system (not shown) interrogates the sensor 236 and obtains abaseline measurement. In one example, the inspection system caninterrogate the sensor 236 to detect any changes in the refractive indexat or near the sensing surface while the buffer solution is flowingwithin the flow chamber 232 of the microplate 200. An exemplaryinterrogation system which could interrogate the microplate 200 has beendescribed in a commonly-assigned U.S. patent application Ser. No.11/489,173. However, different types of inspection systems and differenttypes of sensor (if used at all) could be used instead to help performthe flow-through kinetic assay. For instance, the inspection system canbe a grating-based inspection system, a SPR inspection system, afluorescent detection inspection system, an acousto-optic detectioninspection system, a visual inspection system (sensors not required), ora capacitive detection inspection system.

At step 406, the fluid delivery system 300 stops the flow of the buffersolution after the inspection system obtains the baseline measurement.Then, at step 408, the fluid delivery system 300 causes an analytesolution (which would contain the drug to be tested) to flow through thesecond fluid delivery tip 304 b into and through the flow chamber 232and then out the fluid removal tip 306 while an inspection system (notshown) interrogates the sensor 236 and obtains an associationmeasurement. As discussed below, the flow chamber 232 is speciallyconfigured to enable a fast switch time between the flowing of thebuffer solution and the analyte solution to obtain the baselinemeasurement and the association measurement.

At step 410, the fluid delivery system 300 stops the flow of the analytesolution after the inspection system obtains the associationmeasurement. Then, at step 412, the fluid delivery system 300 causes thebuffer solution to flow again through the first fluid delivery tip 304 ainto and through the flow chamber 232 and then out the fluid removal tip306 while an inspection system (not shown) interrogates the sensor 236and obtains a disassociation measurement. The sensor responses and inparticular the baseline measurement, association measurement, anddisassociation measurement can be used to calculate the rate at which adrug (within the analyte solution) or like analyte associates with atarget (immobilized on the sensing surface in the flow chamber 232) andthen dissociates from the immobilized target.

This process and the resulting measurements are significant to properlytest a new drug candidate. Plus, to obtain these measurements it isuseful to have a fast switching time between the flowing of the buffersolution, the analyte solution, and the buffer solution during steps404, 408 and 412. The sensor response times, particularly during theassociation phase, can be on the order of about 1-100 seconds. Thus, tomonitor the shortest response times it is useful that the switching timefrom flowing the buffer solution to the analyte solution and back tobuffer solution be at least as short, and preferably much shorter, thanthe time it takes the drug to completely bind to the immobilized target.Otherwise, the resulting kinetic response will be confounded by the slowfluidic switching. To address this issue, the flow chamber 232 has beendesigned to have a special configuration that minimizes the fluid switchtime. Several different flow chambers 232 that can be used, each withdifferent configurations, are discussed next with respect to FIGS. 5-11.

Referring to FIGS. 5A-5B, there are perspective views of an exemplaryflow chamber 232 a in embodiments of the disclosure. Prior to discussingthe configuration of the exemplary flow chamber 232 a, it should benoted that FIG. 5A illustrates the path lines of a fluid that isinserted into the first fluid inlet 224 a and flowing through the flowchamber 232 a before being removed via the fluid outlet 226. FIG. 5Billustrates the residence flow time associated with a fluid flowingwithin the flow chamber 232 a where the light portions correspond withgreater than about 10 seconds of residence time, the dark portionscorrespond with about 0 seconds of residence time, and the gray portionscorrespond with about 0-10 seconds of residence time.

As shown, the exemplary flow chamber 232 a has a first inlet portion502, a first flow restrictive neck 504, a second inlet portion 506, asecond flow restrictive neck 508, a central portion 510, and an outletportion 512. The first inlet channel 224 a (or first fluid inlet 224 a)is in fluid communication with the first inlet portion 502. The firstinlet portion 502 is in fluid communication with the first flowrestrictive neck 504. Likewise, the second inlet channel 224 b (orsecond fluid inlet 224 b) is in fluid communication with the secondinlet portion 506. The second inlet portion 506 is in fluidcommunication with the second flow restrictive neck 508. The first andsecond flow restrictive necks 504 and 508 are in fluid communicationwith the central portion 510. In this example, the central portion 510also has a flow restrictive neck 514 which is in fluid communicationwith the first and second flow restrictive necks 504 and 508. Also, inthis example there is a sensor 236 which has a sensing surface that islocated within the central portion 510. Lastly, the outlet portion 512is in fluid communication with the central portion 510 and the fluidoutlet channel 226 (or fluid outlet 226).

The flow chamber 232 a can be configured to effectively minimize theswitch time associated with completing steps 404, 406, 408, 410 and 412which is significant when performing a flow-through kinetic assay. Inparticular, the first flow restrictive neck 504 can be sized to minimizeand possibly eliminate the buffer solution from flowing into the secondinlet portion 506 and up the second fluid inlet 224 b during steps 404and 412. Likewise, the second flow restrictive neck 508 can be sized tominimize and possibly eliminate the analyte solution from flowing intothe first inlet portion 502 and up the first fluid inlet 224 a duringstep 408. The flow restrictive neck 514 is sized to assure that eitherthe buffer solution or the analyte solution flows directly over thesensing surface in the central portion 510 during steps 404, 408 and412. For instance, the flow chamber 232 a can be about 1 to about 5 mmwide, about 2 mm to about 8 mm long and about 10 to about 500 μm high.The first and second flow restrictive necks 504 and 508 can be about 100to about 1000 μm wide and about 200 μm to about 3000 μm long. The flowrestrictive neck 514 within the central portion 510 can be about 200 μmto about 1500 μm wide and about 200 μm to about 1500 μm long.

Referring to FIGS. 6A-6H, there are shown top views of four exemplaryflow chambers 232 b, 232 c, 232 d and 232 e in embodiments of thedisclosure. The exemplary flow chamber 232 b has the same configurationas the aforementioned flow chamber 232 a except that the central portion510 does not have a flow restrictive neck 514 (see FIGS. 6A-6B). Theexemplary flow chamber 232 c has the same configuration as theaforementioned flow chamber 232 a except that there is no sensor 236(see FIGS. 6C-6D). The exemplary flow chamber 232 d has the sameconfiguration as the aforementioned flow chamber 232 a except that thecentral portion 510 is narrower than the central portion 510 in flowchamber 232 a (see FIGS. 6E-6F). The exemplary flow chamber 232 e hasthe same configuration as the aforementioned flow chamber 232 a exceptthat the central portion 510 is narrower than the central portion 510 inflow chamber 232 a and the sensing surface associated with the sensor236 is smaller which can yield slightly faster switch times due to theaveraging of a smaller area (see FIGS. 6G-6H). FIGS. 6C-6H illustrateexemplary flow chambers 232 c, 232 d and 232 e where the first flowrestrictor neck 504 has an output opening that is directly opposite froman output opening of the second flow restrictor neck 508. FIGS. 6A, 6C,6E and 6G illustrate the path lines of a fluid that is inserted into thefirst fluid inlet 224 a (associated with the first inlet portion 508)and flowing through the flow chamber 232 b, 232 c, 232 d and 232 ebefore being removed via the fluid outlet 226 (associated with theoutlet portion 510). FIGS. 6B, 6D, 6F and 6H illustrate the residenceflow time associated with a fluid flowing within the flow chambers 232b, 232 c, 232 d and 232 e where the light portions correspond withgreater than about 10 seconds of residence time, the dark portionscorrespond with about 0 seconds of residence time, and the gray portionscorrespond with about 0 to about 10 seconds of residence time.

The flow chamber 232 of the disclosure is a marked-improvement over therectangular flow chamber disclosed in the parent patent application(U.S. patent application Ser. No. 11/784,130) at least when it is usedto perform a flow-through kinetic assay as described herein with respectto FIG. 4. FIGS. 7A-7B are diagrams of the rectangular flow chamber 700which has two fluid inlets 702 and 704 and one fluid outlet 706. FIG. 7Aillustrates the path lines of a fluid that is inserted into the firstfluid inlet 702 and flowing through the rectangular flow chamber 700before being removed via the fluid outlet 706. FIG. 7B illustrates theresidence flow time associated with a fluid flowing within therectangular flow chamber 700 where the light portions correspond withabout 10 seconds of residence time, the dark portions correspond withabout 0 seconds of residence time, and the grey portions correspond withabout 0 to about 10 seconds of residence time. As can be seen, the fluidwhich is flowing from the first inlet 702 is also flowing near and intothe second inlet 704 which may be undesirable and can adversely affectthe switch times between steps 404, 406, 408, 410 and 412.

FIGS. 8A-8B respectively illustrate perspective views of the rectangularflow chamber 700 and the exemplary flow chamber 232 a of the disclosure.These views illustrate the pressures measured when there is a fluidinserted into one fluid inlet 702 and 224 a and flowing through therectangular flow chamber 700 and the exemplary flow chamber 232 a andout the fluid outlet 706 and 226. The exemplary flow chamber 232 a has arelatively large pressure drop in the first flow restrictive neck 504such that once the fluid leaves the first flow restrictive neck 504 thepath of least resistance is to the fluid outlet 226, rather than partlyto the fluid outlet 226 and the partly across the central portion 510 tothe second fluid inlet 224 b as is the instance with the rectangularflow chamber 700. The effect of this is a minimization of cross flow anddiffusion up the second fluid inlet 224 b in the exemplary flow chamber232 a which is important when trying to minimize rise time once a fluidstarts to flow into the fluid inlet 224 b. FIG. 9 is a plot of risetimes which shows that all of the exemplary flow chambers 232 a, 232 b,232 c, 232 d and 232 e show a step-change reduction in rise time overthe rectangular flow chamber 700 when flowing a fluid through one fluidinlet 224 a and 702 and then stopping that flow and starting to flowanother fluid through the other fluid inlet 224 b and 704. This testused flow chambers with a 50 μm channel height and a 50 μL/min flowrate.

The flow chamber 232 can be further improved by reducing the sizes ofthe first and second inlet portions 502 and 506 which enhance theadvantages of having the first and second flow restrictive necks 504 and508. In particular, the flow chamber 232 can be further improved byreducing the diameters of the first and second inlet portions 502 and506 which further minimizes the fluidic switch time beyond the levelsdemonstrated in FIG. 9. FIGS. 10A and 10B respectively illustrateperspective views of the aforementioned exemplary flow chamber 232 a andan enhanced flow chamber 232 f. The exemplary flow chamber 232 a shownhas first and second inlet portions 502 and 506 which are 1.0 mm indiameter. While, the enhanced flow chamber 232 f has first and secondinlet portions 502′ and 506′ which are 0.5 mm in diameter. This testused flow chambers with a 50 μm channel height and a 100 μl/min flowrate.

FIG. 11 is a plot that shows a comparison of the rise times for bothflow chambers 232 a and 232 f. The fundamental reason for the reductionin rise time in flow chamber 232 f is the diameter reduction in thefirst and second inlet portions 502′ and 506′. In this test, the flowchamber 232 a had first and second flow restrictive necks 504 and 508which had a volume of 0.8 microliters and the first and second inletportions 502 and 506 each had a volume of 2.4 microliters. Clearly,further reduction of the height or width of the first and second flowrestrictive necks 504 and 508 would not significantly reduce the totalvolume as much as reducing the diameter of the first and second inletportions 502 and 506. Thus, by reducing the diameters of the first andsecond inlet portions 502 and 506 from 1 mm to 0.5 mm the volume wasreduced from 2.4 microliters to 0.6 microliters. The diameters of thefirst and second inlet portions 502 and 506 could further be reduced to,for example, 0.25 mm if desired. In this way, the flow chamber 232 f hasa total volume in the first inlet portion 502′ and the first flowrestrictive neck 504′ of 1.4 microliters (0.8 microliters+0.6microliters). While, the flow chamber 232 a has a total volume in thefirst inlet portion 502 and the first flow restrictive neck 504 of 3.2ul (0.8 microliters channel+2.4 microliters hole) which is 56% more thanthe corresponding sections in flow chamber 232 f.

The dual inlet microchannel device 100 (with the specially configuredflow chamber 110) and the microplate 200 (with the specially configuredflow chambers 232) can be effectively used in flow-through kineticassays. In addition, the dual inlet microchannel device 100 and themicroplate 200 have other uses and advantages, for example:

-   -   The flow chamber 110 and 232 employs geometric flow restrictions        that function like valves, reducing mechanical complexity and        cost.    -   The design of the fluidic handling system 300 can be greatly        simplified since the fluidic restrictions are integrated into        the flow chamber 110 and 232.    -   The flow chamber 110 and 232 which has the flow centering        assures efficient purging of fluid over the sensor 112 and 236        for fast rise times.    -   The flow chamber 110 and 232 can be incorporated within various        types of devices and microplates other than the ones described        herein.    -   The dual inlet microchannel device 100 and the microplate 200        can be used to perform other types of assays in addition to the        flow-through kinetic assay described herein. For instance, dual        inlet microchannel device 100 and the microplate 200 can be used        in assays that require two or more fluids to flow at the same        time through the flow chambers 110 and 232.

The flow chamber 110 and 232 effectively enables the fast switch timesin the fluid flows by using pressure balancing which is made possible bythe first inlet portion 114 and 502, the first flow restrictive neck 116and 504, the second inlet portion 118 and 506 and the second flowrestrictive neck 120 and 508. However, the pressure balancing within theflow chamber can also be accomplished in other ways such as: 1) locallydecreasing the channel height by building a step or small weir aroundthe areas that are associated with the fluid inlets 224 a and 224 b; or2) embedding a porous membrane in the inlet areas that are associatedwith the first and second flow restrictive necks 504 and 508. Exemplarydual inlet microchannel devices that incorporate these alternative flowchambers are discussed with respect to FIGS. 12 and 13.

FIGS. 12A-12B respectively illustrate a cross-sectional side view and across-sectional top view of a dual inlet microchannel device 1200 inembodiments of the disclosure. The dual inlet microchannel device 1200includes a body 1202 having located therein a first fluid inlet 1204, asecond fluid inlet 1206, a fluid outlet 1208, a flow chamber 1210, andan optional sensor 1212. The flow chamber 1210 includes a first weir1214 (first flow restrictor 1214), a second weir 1216 (second flowrestrictor 1216), a central portion 1218, and an outlet portion 1220.The first weir 1214 and the second weir 1216 each have a height that isabout 50 to about 90% of the height of the flow chamber 1210. The firstweir 1214 is associated with the first fluid inlet 1204. The second weir1216 is associated with the second fluid inlet 1206. The first weir 1214and the second weir 1216 are both associated with one end of the centralportion 1218 while an opposite end of the central portion 1218 isassociated with the outlet portion 1220 and the fluid outlet 1208. Thesensor 1212 if used would have a sensing surface that would be locatedwithin the central portion 1218. In this example, the flow chamber 1210has a rectangular shape but if desired the flow chamber 1210 could havethe same shape as any of the aforementioned flow chambers 232 where theweirs 1214 and 1216 could be respectively placed at the interfacebetween the fluid inlet portions 114 and 116 and the flow restrictivenecks 116 and 120. The microplate 200 could incorporate these flowchambers 1210 instead of the aforementioned flow chambers 232. Plus, themethod 400 could be implemented with these flow chambers 1210 instead ofthe aforementioned flow chambers 232.

FIGS. 13A-13B respectively illustrates a cross-sectional side view and across-sectional top view of a dual inlet microchannel device 1300 inembodiments of the disclosure. The dual inlet microchannel device 1300includes a body 1302 having located therein a first fluid inlet 1304, asecond fluid inlet 1306, a fluid outlet 1308, a flow chamber 1310, andan optional sensor 1312. The flow chamber 1310 includes a first porousmaterial 1314 (first flow restrictor 1314), a second porous material1316 (second flow restrictor 1316), a central portion 1318, and anoutlet portion 1320. The first porous material 1314 is associated withthe first fluid inlet 1304. The second porous material 1316 isassociated with the second fluid inlet 1306. The first porous material1314 and the second porous material 1316 are both associated with oneend of the central portion 1318 while an opposite end of the centralportion 1318 is associated with the outlet portion 1320 and the fluidoutlet 1308. The sensor 1312 if used has a sensing surface locatedwithin the central portion 1318. As shown, the first and second porousmaterials 1314 and 1316 have the form of plugs that are respectivelylocated within the fluid inlets 1304 and 1306. Alternatively, the firstand second porous materials 1314 and 1316 can have the form of platesthat have the same diameter as the fluid inlets 1304 and 1306 and arelocated next to or just below the openings in the fluid inlets 1304 and1306. In embodiments, the first and second porous materials 1314 and1316 can have the form of sheets that are positioned to cover theopenings of the fluid inlets 1304 and 1306 and can be sized to be largerthan the openings of the fluid inlets 1304 and 1306 but not so large asto be located over the sensor 1312. In this example, the flow chamber1310 has a rectangular shape but if desired the flow chamber 1310 couldhave the same shape as any of the aforementioned flow chambers 232. Themicroplate 200 could incorporate these flow chambers 1310 instead of theaforementioned flow chambers 232. Plus, the method 400 can beimplemented with these flow chambers 1310 instead of the aforementionedflow chambers 232.

Although several embodiments of the disclosure have been illustrated inthe accompanying Figures and described in the Detailed Description, itshould be understood that the invention is not limited to theembodiments disclosed, but is capable of numerous rearrangements,modifications and substitutions without departing from the spirit of theinvention as set forth and defined by the following claims.

The invention claimed is:
 1. A dual inlet microchannel devicecomprising: a body having formed therein: a first fluid inlet; a secondfluid inlet; a fluid outlet; and a flow chamber comprising: a first flowrestrictive neck associated with the first fluid inlet; a second flowrestrictive neck associated with the second fluid inlet; a centralportion having one corner of one end associated with the first flowrestrictive neck and another corner of the one end associated with thesecond flow restrictive neck; an outlet portion associated with thefluid outlet and an opposite end of the central portion, wherein theopposite end is directly opposite from both an opening of the one cornerand an opening of the another corner associated with the one end of thecentral portion; wherein the first fluid inlet is a buffer solutioninlet and the second fluid inlet is an analyte solution inlet, andwherein the first flow restrictive neck has an output opening directlyopposite an output opening of the second flow restrictive neck; whereinthe flow chamber has a height of about 10 μm-500 μm, a length of about 2mm-8 mm, and a width of about 1 mm-5 mm; and wherein the first flowrestrictive neck and the second flow restrictive neck fluid inlet eachhas a width of about 100 μm-1000 μm, and a length of about 200 μm-3000μm.
 2. The device of claim 1, further comprising a sensor that has asensing surface located within the central portion of the flow chamber.3. The device of claim 1, wherein the flow chamber further includes: afirst inlet portion located between the first fluid inlet and the firstflow restrictive neck; a second inlet portion located between the secondfluid inlet and the second flow restrictive neck; and wherein the firstfluid inlet portion and the second fluid inlet portion each has adiameter of about 0.25 mm-1 mm.
 4. The dual inlet microchannel device ofclaim 1, wherein the central portion further includes a third flowrestrictive neck associated with the first flow restrictive neck and thesecond flow restrictive neck; and wherein the third flow restrictiveneck has a width of about 200 μm-1500 μm, and a length of about 200μm-1500 μm.
 5. A dual inlet microchannel device comprising: a bodyhaving formed therein: a first fluid inlet configured to receive a firstsolution; a second fluid inlet configured to receive an second solution;a fluid outlet; and a flow chamber configured to have a fast switch timebetween having either the first solution or the second solution flowingtherein, wherein the flow chamber comprises: a first flow restrictiveneck associated with the first fluid inlet; a second flow restrictiveneck associated with the second fluid inlet; a central portion havingone corner of one end associated with the first flow restrictive neckand another corner of the one end associated with the second flowrestrictive neck; an outlet portion associated with the fluid outlet andan opposite end of the central portion, wherein the opposite end isdirectly opposite from both an opening of the one corner and an openingof the another corner associated with the one end of the centralportion; wherein said flow chamber is configured such that when only thefirst solution is flowing therein there is a pressure drop in the firstflow restrictive neck such that once the first solution leaves the firstflow restrictive neck then a path of least resistance for a flow of thefirst solution is to the outlet portion and the fluid outlet rather thanpartly to the outlet portion and the fluid outlet and partly across thecentral portion to the second flow restrictive neck and the second fluidinlet; wherein said flow chamber is configured such that when only thesecond solution is flowing therein there is a pressure drop in thesecond flow restrictive neck such that once the second solution leavesthe second flow restrictive neck then a path of least resistance for aflow of the second solution is to the outlet portion and the fluidoutlet rather than partly to the outlet portion and the fluid outlet andpartly across the central portion to the first flow restrictive neck andthe first fluid inlet; wherein the first fluid inlet is a buffersolution inlet and the second fluid inlet is an analyte solution inlet,wherein the first solution is a buffer solution and the second solutionis an analyte solution, and wherein the first flow restrictive neck hasan output opening directly opposite an output opening of the second flowrestrictive wherein the flow chamber has a height of about 10 μm-500 μm,a length of about 2 mm-8 mm, and a width of about 1 mm-5 mm; and whereinthe first flow restrictive neck and the second flow restrictive neckfluid inlet each has a width of about 100 μm-1000 μm, and a length ofabout 200 μm-3000 μm.
 6. The dual inlet microchannel device of claim 5,further comprising a sensor that has a sensing surface located withinthe central portion of the flow chamber.
 7. The dual inlet microchanneldevice of claim 5, wherein the flow chamber further includes: a firstinlet portion located between the first fluid inlet and the first flowrestrictive neck; a second inlet portion located between the secondfluid inlet and the second flow restrictive neck; and wherein the firstfluid inlet portion and the second fluid inlet portion each has adiameter of about 0.25 mm-1 mm.
 8. The dual inlet microchannel device ofclaim 5, wherein the central portion further includes a third flowrestrictive neck associated with the first flow restrictive neck and thesecond flow restrictive neck; and wherein the third flow restrictiveneck has a width of about 200 μm-1500 μm, and a length of about 200μm-1500 μm.
 9. A dual inlet microchannel device comprising: a bodyhaving formed therein: a first fluid inlet; a second fluid inlet; afluid outlet; and a flow chamber comprising: a first flow restrictiveneck associated with the first fluid inlet; a second flow restrictiveneck associated with the second fluid inlet; a central portion havingone corner of one end associated with the first flow restrictive neckand another corner of the one end associated with the second flowrestrictive neck; an outlet portion associated with the fluid outlet andan opposite end of the central portion, wherein the opposite end isdirectly opposite from both an opening of the one corner and an openingof the another corner associated with the one end of the centralportion; the central portion further comprises a third flow restrictiveneck associated with the first flow restrictive neck and the second flowrestrictive neck; the flow chamber has a height of about 10 μm-500 μm, alength of about 2 mm-8 mm, and a width of about 1 mm-5 mm; the firstflow restrictive neck and the second flow restrictive neck fluid inleteach has a width of about 100 μm-1000 μm, and a length of about 200μm-3000 μm; and the third flow restrictive neck has a width of about 200μm-1500 μm, and a length of about 200 μm-1500 μm.
 10. The dual inletmicrochannel device of claim 9, further comprising a sensor that has asensing surface located within the central portion of the flow chamber.11. The dual inlet microchannel device of claim 9, wherein the flowchamber further includes: a first inlet portion located between thefirst fluid inlet and the first flow restrictive neck; a second inletportion located between the second fluid inlet and the second flowrestrictive neck; and wherein the first fluid inlet portion and thesecond fluid inlet portion each has a diameter of about 0.25 mm-1 mm.